but I don't think wanting women around a sausage fest is sexist. It's being male.
Sure, that's being (heterosexual) male, but you are making the same assumption as the original event-planners did: all of our attendees will be male. There is nothing in the subject material of the event (their API discussion or whatever) that would interest a female.
This is the thinking that strikes me as sexist: all developers are male, so we only need to appeal to males to make our events appealing.
Actually, this is one of the things that is so sad about this case - they had already taken a number of steps to get away from the classic hack-a-thon stereotype of a bunch of sweaty fat geeks eating pizza. They were putting on quality food (including, apparently, chocolate and cupcakes, which I would suggest, have quite strong female appeal - not to, you know, stereotype...). They also offer massages and gym passes, which I think extend the appeal of the event outside the traditional geek stereotype in a way that suggests 'women welcome'.....
... right up until the line where they suggest that having female serving staff bring you beer while you code is another perk, on the same level as those others. At which point you reassess the massages and gym-passes in the context of this new information and realise that there might be a totally different vibe to this event than the cupcakes-and-chocolate-with-access-to-a-gym-to-burn-off-the-excess-calories-and-a-nice-massage-at-the-end-of-the-day a female coder might have, up until that point, been imagining...
Seriously, take out the sexism, and I think they were well on their way to figuring out the recipe for creating an event with cross-gender appeal.
Mostly by not doing things like hiring a bunch of women to serve beer and listing it as a perk. It's then appealing to anyone interested in the topic, regardless of anything.
Just don't do things that explicitly cater to "FOO" if your intentions are not to explicitly cater to group "FOO", particularly if those things include offering up people of group "BAR" as an incentive to come.
Should you do things to make your hackathon appealing to programmers? Yes. These things are food, drinks, subject matter/activities and socialization with other programmers. Food and drinks appeal to humans, and you don't want a bunch of people having heatstrokes or diabetic comas. Subject matter/activities and other programmers being there to socialize with appeal to programmers. Pretty much all programmers who would want to attend a hackathon.
